1. Field of the Invention
The invention pertains to the field of cutting. More particularly, the invention pertains to a method and apparatus for precision cutting of filamentary substances to predetermined lengths.
2. Description of Related Art
Electronic devices such as printed wiring boards are often connected so that data can pass from one device to the other. As the trend toward electronic component miniaturization continues, the volume of such data continues to increase. This requires that the contacts between the electronic devices be of a high density.
Often, electronic components are interconnected by a system of contacts referred to as a Land Grid Array (LGA), which typically contains electrical interposers to provide an effective connection medium. LGA interposers, in turn, contain inserted conductive xe2x80x9cbuttons.xe2x80x9d The manufacturing of such buttons entails defect free cutting of a conductive elastomer cable medium into ultra-precise segments. The elastomer cable consists of a number of thin metallic filamentary materials that conduct electricityxe2x80x94i.e., wires, embedded in an elastomeric body, that is, a body made out of an elastic material resembling rubber. The ultra-precise segments of the cable become buttons once they are inserted into the LGA carrier.
The manufacture of ultra-precise segment buttons such as those described above poses unique problems, as the cable-slices must be precisely and cleanly cut, of consistent length, and possessing of no surface defects, such as distorted conductors or torn elastomer. Among the chief challenges are ensuring that the elastomer cable is not damaged during cuttingxe2x80x94which would result in defects that would raise the contacts resistance beyond that of industrial standardsxe2x80x94and ensuring that the buttons are of extremely short and consistent length. In sum, there is a need to slice a thin cable into ultra precise slices of consistent length with no defects in the resulting segments.
In the prior art, several techniques were developed to perform this high-precision cutting job. These techniques include laser, water jet, X-ACTO knife, scissors, wire cutters and razor blade methods. The water jet and laser approaches were expensive, while the other methods resulted in cuts of poor quality. Accordingly, there remains a need in the industry for an inexpensive, yet highly effective, method of slicing elastomeric cable into ultra-precise, undamaged segments of consistent length.
The invention discloses a method of cutting an elastomer cable into ultra-precise segments of consistent length with a high level of confidence that the top and bottom of the segments will be smooth and otherwise free of defects. The invention also discloses an apparatus, called a xe2x80x9ccutter,xe2x80x9d for performing such cuts. The cutter is an elastomer cable slicer with adjustable feed, clamping die and sawing razor action. The cutter uses one or more single-edge razor blade(s) for sawing purposes; such blade(s) transverse the surface of a die that holds the elastomer cable. A clamp holds the cable in place during cutting and a mechanical feed mechanism advances the cable to provide accurate and adjustable feed lengths. The cutter of the present invention can be reliably integrated into a high throughput rate manufacturing process.